Trans Yoke Loosening Up

[swebster]

Does anyone know the correct torque specifications for the transmission yoke bolt? I've tightened this thing three times (the last adding a lock washer) and it keeps coming loose every 1000 miles or so.

When I say loose I mean maybe 1/4 - 1/2 turn. But it's enough to allow the yoke to "float" in it's splines causing that blasted vibration when at speed and under no/low load. Tightening it up removed the vibration immediately.

I'm getting pretty good at dropping the driveshaft and tightening everything up but I wonder why this bolt is not staying put. Was it over torqued? Should I replace the bolt? What about lock tite?

I need to repair my parking break this weekend so it will be a good time for me to tighten the yoke one FINAL time.

[thenewkid64]

Steven,

Are you describing the two bolts that hold the tail of the transmission to the cross member?

[swebster]

Brett,
No, sorry I wasn't clear. Its actually the [male] splined yoke that connects the driveshaft to the [female] shaft in the transmission tail. First U-Joint is on the aft end. If you remove the U-Joint there is a big ole bolt in the center of it that passes through the yoke and into the tranmission output shaft.

[thenewkid64]

OK,

I was wondering because the bolts that held the tail to the cross member were not doing their job on mine. The bolts thread into an aluminum housing??? The holes go all through so they now have longer bolts with a nut on the back side to hold it all in place.

Are you torquing the bolt to the proper number of ft/lbs? What about using a bit of thread locker?

[swebster]

Well that's the thing; I don't know the specifications. I just tighten it as much as I can with a big 1/2 socket wrench. Which is hard to do since you under the coach, mid coach and you can't really get too much leverage. I haven't had any trouble with the tailhousing (yet).

I've been considering using the impact wrench on it (if it's spec to 100 ft-lbs) but obviously DO NOT want to stripe this one out.....ouch - that would hurt!

[George]

steve,
Seems like you been having trouble with that yoke before, vibration,seal replacement, now it loosening up.
Check to see everything is true. Is the output shaft possibly bent? is the yoke true?
Jack up one rear set duels, block the others GOOD, and have someone (you trust) not someone that might be a recipant of your ins. policy, Ha,lol! put it in gear.
SLOWLY let it turn over(idle in gear) and check runout. you need not run it above idle.
Use common sence here.
OR you could remove the rear half of the drive shaft (seems like the front half is supported by the midship bearing and watch what is happening.
Did they replace the rear bushing in the trans when it was overhauled, many overlook this bushing?
ol'George

[overlander63]

Originally Posted by swebster@myrvadvanta

Brett,
No, sorry I wasn't clear. Its actually the [male] splined yoke that connects the driveshaft to the [female] shaft in the transmission tail. First U-Joint is on the aft end. If you remove the U-Joint there is a big ole bolt in the center of it that passes through the yoke and into the tranmission output shaft.

Steven, the last one I did I torqued to 150 lbs/ft, and used locktite on the threads. I have had no more problems with the offending part since.
Terry

[PeterH-350LE]

Good info from George!!
On a previous MH I finally traced elusive vibration to a worn yoke. To be more specific the ears of the yoke were worn enough to allow the first u-joint to be installed ever so slightly off center. Not a very expensive part to replace and possibly essential on a high mileage coach.

Originally Posted by George

steve,
Seems like you been having trouble with that yoke before, vibration,seal replacement, now it loosening up.
Check to see everything is true. Is the output shaft possibly bent? is the yoke true?
Jack up one rear set duels, block the others GOOD, and have someone (you trust) not someone that might be a recipant of your ins. policy, Ha,lol! put it in gear.
SLOWLY let it turn over(idle in gear) and check runout. you need not run it above idle.
Use common sence here.
OR you could remove the rear half of the drive shaft (seems like the front half is supported by the midship bearing and watch what is happening.
Did they replace the rear bushing in the trans when it was overhauled, many overlook this bushing?
ol'George

[swebster]

Thanks to all for this great info.

George - good points. I'm not sure I trust anyone I usually work with enough to perform this test safely. Not that they are untrustworthy - just that they don't have a lot of experience around autos, trucks, etc.

Terry - thanks there is no way I got 150 on there. I might hit it with the impact wrench next time. If it loosens again I'll either replace or take it to the truck shop for a runout check.

No idea on the bushing replacement. I only replaced the seal.

[George]

Steve,
The more I think about it, seems like that yoke should not cause vibration even if it IS loose, granted, it IS shorter than a regular slip yoke.
With the bolt out of it, see if you can get it to move around,(side to side) it should be a snug fit.
It should slide on but not have too much clearance between it and the OUTPUT shaft.
Be advised that the output shaft(in trans) WITHOUT the yoke WILL have noticeable side to side movement, this is normal, but with the yoke IN the trans, the bushing should allow only slight side to side movement
Summing things up:
We are checking TWO things here, looseness between the splined output shaft and the yoke,--- AND--- looseness of the yoke IN the trans bushing.
things should be "GOOT "N" TIGHT" as ARNOLD would say. :^)

ol'George

[swebster]

George - if I remember form the last time I did this when the bolt loosens up it will allow the yoke to slide forward and backward a little (1/8" - 1/4") on it's splines. I'll be back under there to re-tighten this week to I'll check side to side play and lateral play as well.

I suspect this was loose for a while before I aquired the coach. It took me the longest time to find the source of this vibration and noise and now that it keeps coming back I want to make it go away for longer than 2000 miles!

[87MH]

Originally Posted by swebster@myrvadvanta

.......I want to make it go away for longer than 2000 miles!

Out of curiosity (and the quest for knowledge) I contacted the shop which recently overhauled the transmission on the Xeppelin.

They stated that Locktite (Locktight?) goes onto all of these types of bolts (evidently they do LOTS of GM truck and P-3X chassis work).

I asked about torque on the bolt, the reply was "just tight", since no bearings or flat surfaces are mating - just holding the assembly on the splines.

On Steven's coach, I wonder if something else could be out of alignment or worn causing his vibration and back-off failures.

[74Argosy24MH]

Replace the bolt and locktite it (clean the threads in the shaft well), even with vibration it shouldn't back off. When you replace carrier bearings and u joints (vibration) it doesn't have to be tightened.

John

[swebster]

OK...I'll try a new bolt with locktite. I already replaced both carrier bearings and all of the ujoints so there's not much left.

[George]

Steve,
use any solvent (Brake cleaner, lacquer thinner etc.) to clean the oil from the
thread(S) and blow it dry, otherwise the locktite will be useless.
Look at locktite as a "paint" and procede as you would prepair an item for "paint".
And as stated before, check to see if the yoke is slopy on the spline, if it is, Nothing will keep it tight,except replacement.
Luck,
ol'George

[joepospisil]

Check the Drive shaft timing. If the drive shaft has been disassembled at the slip yoke in the center of the drive shaft and not put back in time the joints will be out of sequence and shake heck out of the drive line. Have a drive line shop check the joint timing at the slip yoke and you may find the reason for the vibrations.

Joe

[74Argosy24MH]

The slip joint has a double width 'key' so it can only be assembled one way.

John

[wb13798]

i developed a vibration while in traffic in Atlanta. or that is where i noticed it. it has become a real irritant, cant drive at speeds of 57 to 62 mph.can but don't want to. i can feel it when it starts in the steering wheel and as i gets worse in the seat.
i did an inspection of the drive line and all looks OK. one u joint has some play but not enough to do the vibration that i am experiencing.
tell me more about this gremlin you have driving you crazy.
my last trip was one thing after another dash ac quit, roof ac quit, gen set don't start. and now i have a vibration that doesn't make sense.
I'm going to get the front tires balanced just make sure it isn't tires. i rotated tires with no change in the vibration. i just love to feed the beast. im about tired of this money pit. a new one cost more than i want to spend. isnt this fun. duh

[74Argosy24MH]

Al

Have someone hold the brake and go slowly from reverse to drive, you should be able to see movement in a u joint (watch the yokes) or the carrier bearing if it is bad.

If you feel it in the steering wheel first I would suspect the front end, worn parts, alignment, tires.

John

[George]

Hi Steve,
Cheer up, once everything is fixed, you will have a nice unit.I have been there with many vehicles. fixed up many a "Klunker" and went on to drive 100,000- 150,000 with out a problem AND it was WAY WAY less expensive than a New Vehicle.

I Reciently experenced a "vibration" in my little 24' Argosy, making a long story short, I had 3 out of 4 rear tires with broken belts and a 4th with a piece out of the tread,as well as broken belts. the "Uni Royal Lorados, were over 10 yrs old.
They had over 90% tread left, so much for good tread. Tires go bad from age as well as use. I knew they were old I was just hoping they would last, given what little I use the coach.
Now I have 6 new tires, Boy, what a differance in ride!!

While under there, I noticed a "wet" Rear Brake hose, long story now it has 3 new hoses, a new master cylinder, and ALL new brakelines.
while at it, I changed the fuel pump hoses, and correctly positioned the trans cooler lines.
kinda like the commercial, "bet ya can't just eat one bite"
One thing leads to another.
BUT the task of moving a pile of dirt is one shovel at a time.
Good luck.
ol George